Re: [Discuss-gnuradio] Filtering USRP FM Reception

[Francesco B.]

Addendum: Apparently it was just a really, really long list of floats that
was a part of a larger away message, but I couldn't scroll up enough when
the terminal wasn't running full-screen. Here's the error message:

Traceback (most recent call last):
  File "usrp_wfm_rcv_filt_nogui.py", line 157, in <module>
    fg = wfm_rx_graph()
  File "usrp_wfm_rcv_filt_nogui.py", line 98, in __init__
    self.connect (self.u, chan_filt, self.guts, self.cleanup,
self.volume_control, audio_sink)
  File
"/usr/local/lib/python2.5/site-packages/gnuradio/gr/basic_flow_graph.py",
line 115, in connect
    self._connect (points[i-1], points[i])
  File
"/usr/local/lib/python2.5/site-packages/gnuradio/gr/basic_flow_graph.py",
line 119, in _connect
    for d in expand_dst_endpoint (dst_endpoint):
  File
"/usr/local/lib/python2.5/site-packages/gnuradio/gr/basic_flow_graph.py",
line 59, in expand_dst_endpoint
    dst_endpoint = coerce_endpoint (dst_endpoint)
  File
"/usr/local/lib/python2.5/site-packages/gnuradio/gr/basic_flow_graph.py",
line 84, in coerce_endpoint
    raise ValueError, "Not coercible to endpoint: %s" % (x,)
ValueError: Not coercible to endpoint: [insert long list of floats here]


Francesco B. wrote:
> 
> Hey all,
> 
> I was wondering, is there anything in particular that's peculiar about
> using a filter to isolate one sine wave out of three that are being
> transmitted over FM? I've attempted adding another FIR (optfir) filter
> post-demod, but connecting it to the pipeline produces a long list of
> small floats in the terminal (filter coefficients, perhaps?), and then the
> program terminates. Otherwise, the program is identical to
> usrp_wfm_rcv_nogui.py. It runs as normal when the filter is commented out,
> outputting all signals at a specific FM frequency to the sound card.
> However, I don't accomplish my task with that.
> 
> What's the proper method for filtering signals, then? It looked fairly
> straightforward, but perhaps optfir doesn't function as I was expecting it
> to. My code is attached.
> 
>  http://www.nabble.com/file/p22029608/usrp_wfm_rcv_filt_nogui.py
> usrp_wfm_rcv_filt_nogui.py 
> 

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